Experimental performance evaluation of the dual-evaporator ejector refrigeration system

The increase in global energy consumption values due to the increasing population also brings negative effects on environmental and climatic effect. Increasing the efficiency of cooling and heating systems has an important place in reducing energy consumption and hydrocarbon emissions. According to the 2018 report of IIR, the energy used for heating and cooling systems constitutes approximately 20% of the total electricity consumed worldwide [1]. For this reason, it is important to develop high efficiency heating or cooling systems that can achieve higher heating and cooling capacities with lower energy consumption. Today, vapor compression refrigeration systems (VCRS) are widely used in cooling and heating applications. In VCRS, expansion devices are used to perform the throttling, operation. However, the expansion devices cause throttling losses and irreversibility, and they adversely affect the system performance. As a solution to this problem, an ejector can be used instead of an expansion device in VCRS. In this study, an experimental refrigeration system is designed to be operated with or without ejector with bypass lines added to the experimental VCRS installed at laboratory scale. In addition, a second evaporator was added to the system and four different operating configurations were created. These configurations are; VCRS is designated as dual evaporator refrigeration system (DES), ejector vapor compression refrigeration system (EVCRC), and dual evaporator ejector refrigeration system (DEES). The experimental system was tested sequentially using R134a as the refrigerant in different configurations. Performance parameters were found by applying energy analysis to the data obtained from the tests. System performance values were analyzed comparatively depending on condenser temperature and refrigerant mass flow rate. Comparison of performance parameters such as cooling capacity of the system, coefficient of performance (COP), compressor power, cooling capacities of evaporator#1 and evaporator#2 are presented in graphics. When the results were examined, it was determined that the mass flow rate in the system increased and the compressor energy consumption decreased with the use of the ejector. However, it was observed that the cooling capacity and COP values obtained from DEES, in which the double evaporator and ejector were used, were higher than the other configurations. It was concluded that the COP value obtained from DEES was 7% to 21% higher than the standard VCRS. As a result of the evaluations, it has been determined that the ejector works more efficiently in systems with dual evaporators and contributes positively to the systems.